Hybrid vehicles and electric vehicles may be powered via a battery pack. Battery packs have a rated capacity that may be expressed in ampere-hours, or energy that may be expressed in watt-hours. If the battery is partially or fully discharged, the battery is storing less than its rated capacity. Battery state of charge (SOC) is one way of expressing the amount of charge stored in the battery relative to the rated battery capacity. For example, if a battery has a capacity of 1000 ampere-hours, the battery has 500 ampere-hours of charge when the battery is at fifty percent SOC.
Battery SOC may also be a basis for determining whether or not a battery may be charged or discharged. If a battery is charged more than a threshold amount, battery degradation may occur. Likewise, if a battery is discharged more than a threshold amount, battery degradation may occur. Therefore, battery charging and/or discharging may be limited to a range or window of battery SOC to reduce the possibility of battery degradation. For example, during nominal operating conditions a battery may be charged to a SOC value of seventy (e.g., seventy percent of rated capacity) and discharged to a SOC value of thirty (e.g., thirty percent of rated capacity). However, restricting or limiting SOC to a specific range or window may reduce an amount of time a vehicle is in a regeneration mode where a vehicle's kinetic energy is stored in the battery for use at a later time. Consequently, the vehicle may have to transition between electric braking and mechanical braking. Further, the vehicle's travel range may be less than is desired after the battery is charged during regenerative braking since battery charging is limited.
The inventors herein have recognized the above-mentioned issues and have developed a system for operating a battery pack of a vehicle, comprising: a vehicle including a battery pack; and a controller including non-transitory instructions for adjusting battery pack charging amount in response to the vehicle traveling on a section of road having a negative grade.
By adjusting a battery pack charging amount in response to a vehicle traveling a section of road having a negative grade or downhill, it may be possible to provide the technical result of extending a range the vehicle travels on electrical energy. Further, the battery pack charging amount may be decreased in response to the vehicle transitioning from traveling a section of road having a negative grade to a section of road having a positive or zero grade. The battery pack charging amount and battery pack rate of charge may be adjusted via increasing and/or decreasing a battery pack state of charge window. The battery pack state of charge window limits the amount of charge supplied to a battery and the rate of charge that may be supplied to the battery.
The present description may provide several advantages. Specifically, the approach may improve vehicle travel distance. Further, the approach may increase battery pack charging for limited durations without degrading battery life. Additionally, the approach may allow the vehicle to operate for longer periods of time while providing regenerative braking.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.